Method of making laminated insulation explosion chamber members



Inventor- Chcuf'Les F. Peterson, 5 m

HLS Attorney.

May 1932- c. F. PETERSON METHOD OF MAKING LAMINATED INSULATION EXPLOSION CHAMBER MEMBERS Filed April 25,.1929

Patented May 24,1932

UNITE sr r CHARLES F. PETERSON, SCOTIA, NEW YORK, ASSIGNOR TO GENEEAL ELECTRIC COM- IRANY, A CORPORATION OF METHOD OF MAKING LAMINATED INSULATION Application filed April 25;

condensation product. The objects of my invention are the provision of an improved method of manufacture of such articles and the provision of improved apparatus by means of which the method may be carried out.

Referring to the drawings, Fig. 1 is a perspective View of a molded insulation explosion chamber member constructed in accordance with my invention; Fig. 2 is a cross section of the same; Fig. 3 illustrates certain steps in the manufacture of the member shown in Figs. 1 and 2; Fig. 4 is an exploded view of the mold forming a part ofmy invention; and Fig. 5 is a cross section through the assembled mold showing the built-up chamber structure therein at the beginning of the curing and pressing stage.

In the copending application of Herman J. H. Huber and Charles R. Kellogg, Serial No. 358,089, filed concurrently'herewith and assigned to the same assignee as the present application, there is'disclosed and claimed an explosion chamber construction for an electric switch in accordance with which construction the explosion chamber member is a one piece member composed entirely of insulating material. This material in order to have the requisite dielectric and mechanical strength is composed of laminations of paper impregnated with a resinous condensation product with the laminations extending continuously circumferentially and longitudinally throughout the structure. Such an explosion chamber member is illustrated in perspective at l in Fig. 1 and in cross section in Fig. 2. I shall now describe how the member may be manufactured.

From paper stock having the desired composition and weight and havingpreviously been impregnated with a resinous condensa- NEW YORK EXPLOSION CHAMBER MEMBERS 1929. Serial No. 358,072.

tion

curved strips 2 are cutand the two long edges areslitted as at 3 and 4 as indicated in Fig. 3. These strips are then at a time around the central conical portion 5 of the dummy 6 with the longer curved edge resting in the annular recessbetween the body portion and the flange 7.. The such length that other on the dummy and in placing themin position care is taken to distribute the joints around the periphery of the dummy. After a number of strips orlayers have thus been applied a securing tape 9 is passed around and tied to hold in positiontemporarily the strips so far applied, The operator then forms the upper fringed portion of the applied strips over the top of the dummy, it being understood that the central portion of the dummy is of such height that the end of the fringe will reach nearly to the center. The plate 10 and weight 11, previously heated,-are quickly applied to the formed over portion and left for a shorttime. The temperature of the plate and weight is sufl'icient to cause a slight softening of the resinous condensation product sufficient only to make the fringedportions at the top to take preliminary form and thereby facilitate the addition of subsequent strips. The above buildingrup process is repeated a suflicient number of imes to use up all of the strips whichby previous calculation is found to be necessary to completely fill the mold hereinafter to be described. The strips 2 preferably are made in a number of different sizes, the larger sizes being applied as the structure becomes built up. Upon completion of this part of the building-up process the resulting structure is ready for the pressure and heattreatment. The mold which I have devised forthistreatment will now be described.

In Fig. 4 I have shown the various parts of the mold in separated relation and in Fig. 5 I have shown them assembled in a hydrau lic press ready to compress the previously described built-up structure. The press is of common construction having the fixed top secured tothe base by the guide columns wrapped, preferably 1 Strips 2 are of the ends lap w llo each product, for example, a phenol-formalif dehyde condensation product, a number of ber 23 on the outer face of which is the spiral 22 is made in two parts together.

member structionof the mold I "as indicatedin Figs 3 on the bottom of the recess 33 a number of drawings.

' supporting member, the latter groove 24. The inner member is secured in place by suitable means, for example, by copper brazing, with the ends of the spiral groove'connecting with the external steam.

or water connections 25.' The core member 27 of the mold has a hollow conical body portion which is constructed to be heated by steam or hot water and like the outermember and similarly secured The inner part 28 has a spiral groove 29 formed on its exterior, the ends of the groove connecting with suitable inlet and outlet pipes, one of which is shown at 30 for the heating fluid. The intermediate member 32 of the mold is in the form of a hollow cone and is composed of aplurality of separate segments, three being shown in the The inner surface of the intermediate'member is shaped to correspond with the desired exterior shape of the finished explosion chamber member, thus an annular recess 33 is formed in it forthe proper shaping of the securing flange of the member. In the bottom of the intermediate mold memher is a recess for receiving the base portion 34: ofthe plug member 35 which when the parts of the mold are pressed together extends into the opening formed therefor in'the core 27. Having thus described the conshall now continue to describe the process of making an explosion chamber member.

"rill of the strips 2 having been applied to the dummy and the fringed portions at one end having been formed over the 37 and 38 are applied to the'exterior and the structure lifted from the dummy. This structure, inverted, is

shown in its present form at 40 and is ready to be placed in the mold. Before inserting it in the intermediate segmental mold memher I place the plug member 35 in position, it temporarily in any suitable manner, and then place in the bottom of the member a number of rings &1 of the same materialas the strips 2 and of various widths and 5. I also place rings 42 of the same material. I then drop the structure 40 into the intermediate mold being held raised relatop oftlie dummy and temporarily held in place as described, securing tapes base. After cooling the tively to the outer member as shown in Fig. 5. Within the structure are nowfldropped several more rings {l3 of the same material.

The upper edge portion of the structure is now given an outward roll as shown in Fig. 5

additional mechanical strength is desired I such ascanvas',

prefer to use a woven fabric, impregnated with a resinous condensation product. in the mold and after attaching core member 35 to core member by suitable means, such, for example, as the rod and chainmemher 45, pass steam or hot water through the passages provided therefor and operate the to slowly apply pressure to the mold. The resinous condensation prod hydraulic press uct being melted by the heat allows the vari= ous layers to slip easily over, each other 'while the structure is taking the form of the mold. In practice I have found it desirable to con.- sume about one half hour while graduallyi-ncreasing the pressure to the maximum amount of 280 tons for a 12 inch chamber. Full pressure is then retainedfor about two hours after which the heat is shut off and the mold gradually cooled by I passing cool water through the passages. During the pressing operation not only does the core member 27 move downward in the intermediate meniber 32 but the latter member also slides downward in the outer member or base 22 in which movement the sectors are drawn together. The side wall portion of the built-up structure thereby is subjected to substantially equal pressure applied to both inner and outer faces. Inasmuch as the thickness of the walls of the finished chamber member is approximately only one third of what it is when the compression is begun it will be seen that were the pressure to be applied from one side only in the usual way the material in all parts of the walls except that near the outer surface would necessarily undergo considerable elongation. With a laminated structure such as I have described the laminations would become ruptured thereby defeating the very purpose of their use. By means of the mold which I have described substantially equal pressure is applied inwardly to both sides of the walls of the article being molded there by avoiding all possibility of rupturing any of the laminations. In buildingup the structure a definite quantity of material including strips and rings is used, measured by weight, which it is found will just fill the mold when full pressure'is applied and the top of-the plug and the top member become flush with the top'of the finished article The" I now insert the core member 27 of vthe intermediate mold and a number of rings l4 of various w dths removed having the appearance of that illustrated in Fig. 1.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. The method of constructing an insulation explosion chamber break switch which comprises applying successive strips of fibrous material impregnated with a resinous condensation product having. slitted edge portions to the sides of a dummy having the the interior of the chamber, forming inwardly over one end of the dummy certain of said slitted edge portions to make the bottom of the chamber member and simultaneousl forming over outwardly the other slitted edge portions to make the attaching flange of the chamber and applying heat and pressure thereto. 7

2. The method of constructing the explosion chamber member of a liquid break switch of insulating material which comprises ap plying to a dummy having a form approximating the interior of the finished member successive strips of fibrous material impregnated with a resinous condensation product and having both edge portions fringed, bending the fringed portion at one edge inwardly over the end of the dummy, adding rings of similar impregnated material at said end of the dummy thereby forming a thickened bottom for the explosion chamber, bending the fringed portions at the opposite edge out- 7 wardly to form a securing flange, and applying heat and pressure to the of the structure thus formed.

3. The method of constructing the explosion chamber member of a liquid break switch of insulating material which comprises applying to a conical dummy having a form approximating the interior of the finished chamber member successive arcuate strips of paper impregnated with a resinous condensation product and having both edges fringed, bending the fringed edges at one side of the strips over the end of the dummy to make chamber member, flaring the bottom of the outwardly the fringed edges at the opposite side of the strips,

reinforcing rings of similarly impregnated material, subjecting the structure to heat and simultaneously applying substantially equal compressive forces against the opposite faces 7 of the walls of the structure.

In witness whereof, I have hereunto set my hand this 29th day of March, 1929;

CHARLES F. PETERSON.

member for a liquid appropriate form for opposite walls applying to this portion CERTIFICATE'OF CORRECTION.

Patent No. 1,860,158. May 24, 1932.

CHARLES F. PETERSON.

It is hereby certified that error appears in the printed specification of,the above numbered patent requiring correction as follows: Page 1, line 55, after the word "preferably" insert the word one; page 2, line 80, for "core" read plug; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 12th day of July, A. D. 1932.

M. J. Moore, (Seal) Acting Commissioner of Patents. 

